Transcript Slide Title

Azimuthal correlation of hadrons in a
partonic/hadronic transport model
Guo-Liang Ma

Background introduction

Model introduction

Analysis method
Results and discussions
Conclusion


High Energy Nucleus-Nucleus Collisions
initial state
hadronic phase
and freeze-out
QGP and
hydrodynamic expansion
pre-equilibrium
hadronization
Physics:
1) Parton distributions in nuclei
2) Initial conditions of the collision
3) a new state of matter – Quark-Gluon Plasma and its properties
4) hadronization
Di-hadron correlations
pT(assoc) > 2 GeV/c
Associated
particles
On away side:
Hard associated
particles →
suppression
pT(assoc) > 0.15 GeV/c
Soft associated
particles →
enhancement
Soft Associated particles on
Away side (thermalization)
What happens to a hard probe that
traverses a colored medium?
SOFTENED
soften + broaden =?= thermalization
near side
away side
thermalization???
BROADENED
BROADENED
SOFTENED
Mach-like cone Structure
Possible interpretations of mach-like cone structure
Wake Effect or “sonic boom”
Θemission= arccos (cs/c)
hep-ph/0411315 CasalderreySolana,Shuryak,Teaney
nucl-th/0406018 Stöecker
Hep-ph/0503158 Muller,Ruppert
nucl-th/0503028 A. K. Chaudhuri
Cherenkov gluon radiation
Θemission= arccos (1/n(p))
PRL 96, 172302 (2006)
Koch, Majumder, X.-N. Wang
Correlation of Jet with flowing medium
hep-ph/0411341 Armesto,Salgado,Wiedemann
AMPT model
a multi-phase transport model
(1) Default AMPT
(2) Melt AMPT
Mix-event Technique
correlation signal in
same event
 (2)Get respective
background by
mixing events in
same centrality
 (3)Get  correlation
by removing
background with
ZYAM method
1/NtrigdNch/d
 (1) Get raw 
530
520
510
500
490
480
470
4608
trig
PT 3-6GeV/c ,PT
asso
0.15-3GeV/c
same event
mix event
20-40%
6
20-40%
4
2
0
-1
0
1
2

3
4
5
Background
Subtracted signal
 correlations from AMPT
(3<pTtrigger<6GeV/c ,0.15<pTassoc<3GeV/c)
1/NtrigdN/d
(1) ▲melt after
Au+Au 200GeV (0-10%)
hadron cascade
8
AMPT 0-10%,(3-6) x (0.15-3)GeV/c
(2) ● melt
7
melt after hadron cascade
before hadron
melt before hadron cascade
default after hadron cascade
6
cascade
default before hadron cascade
Star Data 0-5% (4-6) x (0.15-4)GeV/c factor=1.58
(3)◆ default
5
after hadron
4
cascade
(4)★ default
3
before hadron
2
cascade
1
(5) ■ Star Data
0-5% (40
6)*(0.15-4)GeV/c
-1
0
1
2
3
4
5
factor=1.58
(rad)
Jet remnants character from AMPT
associated Nhadron
16
2
10
(a) PT
trig
PT
trig
14
3-6GeV/c (AMPT)
near
away
4-6GeV/c ( STAR data X factor=1.58)
near
away
trig
PT 4-6GeV/c
(STAR data X factor=1.58)
0-5% away
0-5% near X 0.1
(b)
-1
18
Au+Au 200GeV
dNhadron/dP (GeV/c)
20
1
10
0
10
12
10
-1
10
8
6
trig
PT
-2
10
4
2
-3
3-6GeV/c (AMPT)
0-5% away
0-5% near X 0.1
10
0
2
4
6
8
10
12
0
1
2
(c)
<pT>(Gev/c)
0.9
trig
AMPT data PT 3-6GeV/c
away
trig
STAR data PT 4-6GeV/c
away
(d)
1.0
<PT> (GeV/c)
1.0
0.8
0.7
PT
trig
PT
trig
3
PT (GeV/c)
impact parameter b (fm)
4
3-6GeV/c(AMPT)
away
4-6GeV/c(STAR data)
away
0.9
0.8
0.6
(0-10%)
0.7
0.5
-2
-1
0
- (rad)
1
2
0
2
4
6
8
10
impact parameter b (fm)
12
14
1.2
1.0
0.9
0.8
0.7
0.6
0.5
trig
AMPT PT 2.5-4(GeV/c),PT
associated
1-3.(GeV/c)
melting after hadron cascade
defaulting after hadron cascade
trig
associated
experiment PT 2.5-4(GeV/c),PT
2-3(GeV/c)
0.4
0.3
0.2
1/NtrigdN/d
1/NtrigdN/d
1.1
2
4
6
8
10
impact parameter b (fm)
12
0-10%
0.3
0.2
0.1
-0.1
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
-0.1
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
-0.1
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
-0.1
0
1/NtrigdN/d
spliting parameter D (rad)
 correlations in Au+Au 200GeV
(2.5<pTtrigger<4GeV/c ,1<pTassoc<2.5GeV/c)
0.4
0-10% (2.5-4)X(1-2.5)GeV/c
melt after hadron cascade factor=1/12
melt before hadron cascade factor=1/12
default after hadron cascade factor=1/5
default before hadron cascade factor=1/5
Phenix Data 0-5% factor=1.58
D
0.0
1/NtrigdN/d
Mach-like cone
Structure in AMPT
model
0.5
10-20% (2.5-4)X(1-2.5)GeV/c
melt after hadron cascade factor=1/5
melt before hadron cascade factor=1/5
default after hadron cascade factor=1/2
Phenix Data 10-20% faxtor=1.58
10-20%
20-40% (2.5-4)X(1-2.5)GeV/c
melt after hadron cascade factor=1/5
melt before hadron cascade factor=1/5
default after hadron cascade factor=1/2
Phenix Data 20-40% factor=1.58
20-40%
40-90% (2.5-4)X(1-2.5)GeV/c
melt after hadron cascade factor=1/4
melt before hadron cascade factor=1/4
default after hadron cascade factor=1/2
Phenix Data 60-90% factor=1.58
40-90%
1
(rad)
2
3
Three-particle correlations in AMPT
mix-event technique
background subtracted
3-particle correlation signal
Three-particle correlation density
3-particle correlation
density definition:

d 2N
d1d2

d1d2
region
 d d
1
2
region
70 open: melt before
60 full: melt after
40
30
ratio
center
deflected
cone
near
near-away
50

(a)
20
10
0
0
100
200
Npart
300
2.6 (b)
1.16
2.4
1.12
2.2
1.08
1.04
2.0
1.00
1.8
1.6
open: melt before
1.4 full: melt after
1.2
center/deflected
center/cone
1.0
0
open: melt before
full: melt after
deflected/cone
0 100 200 300
100 N 200
part
300
Parton cascade effect on 2- and 3particle correlation
(1)hadron cascade
mechanism also can
produce 2- and 3-particle
correlation, but it can
not give big enough
splitting parameters.
(2) the parton cascade
mechanism is essential
for describing the
amplitude of
experimental mach-like
structure
Conclusion
1) Di-hadron correlations can be produced by a multiphase transport model(AMPT).
2) Mach-like structure is born in the partonic process
and further developed in hadronic rescattering
process.
3) hadron cascade mechanism can produce dihadron correlation, but it can not give big enough
splitting parameters.
4) Cone , deflected and center 3-particle correlations
all exist in the central Au+Au collisions, however
center 3-particle correlation become more
dominant with the decreasing of Npart .
Thank you